WO2005114828A1

WO2005114828A1 - Rotation control apparatus and method, and electronic device wherein the rotation control apparatus can be used

Info

Publication number: WO2005114828A1
Application number: PCT/JP2005/009414
Authority: WO
Inventors: Norihiro Maeda; Seiichi Yamamoto
Original assignee: Rohm Co., Ltd
Priority date: 2004-05-24
Filing date: 2005-05-24
Publication date: 2005-12-01
Also published as: TWI369066B; JP4944606B2; CN100479321C; CN1943103A; JPWO2005114828A1; US20080067964A1; US7863844B2; TW200616321A

Abstract

A technology for correctly detecting a rotating position of a rotator at the time of rotation start. A rotation control apparatus (10) controls rotation of a motor (90), which includes a stator provided with a plurality of coils (U, V and W) and a rotor having magnetism. At the time of detecting a position of the motor (90) when the motor (90) is stopped, a control part (20) supplies a current to a plurality of different paths including the coils (U, V and W), a stopped position detecting part (50) measures the current flowing in each of the plurality of paths, judges the order of the measured current values, and a rotating position of the motor (90) is detected based on the order. Based on a combination of a path showing the highest current value and a path showing the second highest current value, the stopped time position detecting part (50) judges a position of the motor (90).

Description

Specification

TECHNICAL FIELD The present invention relates to a rotation control device and method, and an electronic apparatus that can use the rotation control device.

The present invention relates to a technique for controlling the rotation of a rotor, and more particularly, to a rotation control device and method for controlling the rotation of a motor including a stator having a plurality of coils and a rotor having magnetism, and the rotation thereof. The present invention relates to an electronic device that can use a control device.

Background art

[0002] A brushless direct current (DC) motor generally includes a rotor having permanent magnets and a stator having coils of a plurality of phases connected in a star connection, and controls a current supplied to the coils. This excites the coil and drives the rotor by rotating it relative to the stator. A brushless DC motor generally includes a sensor such as a Hall element or an optical encoder to detect the rotational position of the rotor, and the current supplied to the coils of each phase is determined according to the position detected by the sensor. Switch to give proper torque to rotor.

[0003] In order to further reduce the size of the motor, a sensorless motor that detects the rotational position of a rotor without using a sensor such as a Hall element has also been proposed (for example, see Patent Document 1). A sensorless motor obtains position information by detecting an induced voltage generated in a coil, for example, by measuring the potential of a midpoint wiring of the motor. Since this sensorless motor obtains position information from an induced voltage generated during rotation of the rotor, there is a problem that the rotational position cannot be known during stoppage. If the motor is started without knowing the rotation position correctly, the rotor may rotate in the direction opposite to the desired rotation direction. For example, when rotating the spindle motor of a hard disk while applying force, it is desirable to minimize the reverse rotation, so it is necessary to properly grasp the rotational position of the motor when starting the motor . In a sensorless motor, a technology for detecting the position of the motor when the motor is started is disclosed, for example, in Patent Documents 1, 2, and 3.

Patent Document 1: JP-A-3-207250

Patent Document 2: JP-A-6-113585

Patent Document 3: JP-A-11 122977 Disclosure of the invention

Problems to be solved by the invention

[0004] In general, in a brushless DC motor, a rotation position is detected at intervals of 60 degrees, and current control is performed in accordance with the detected rotation position. However, in the methods described in Patent Documents 1, 2, and 3, In addition, the rotation angle detected at the start and the rotation angle at the time of control during driving are shifted by 30 degrees. For this reason, it is necessary to correct the rotation angle detected at the time of starting and control the driving force.

The present invention has been made in view of such a situation, and an object of the present invention is to provide a technique for accurately detecting a rotational position at the time of starting a rotor.

Means for solving the problem

[0006] One embodiment of the present invention relates to a rotation control device. The rotation control device includes: a control unit that supplies current to a plurality of different paths including the coils when a motor including a stator having a plurality of coils and a rotor having magnetism is stopped; and a current flowing through the plurality of paths. And a position detector for determining the order of the measured current values and detecting the rotational position of the motor based on the order.

[0007] For example, when the motor includes three types of coils of U-phase, V-phase, and W-phase, the U-phase force also changes to the V-phase, the V-phase force also changes to the U-phase, the V-phase force changes to the W-phase, and the W-phase force V Phase, W-phase force U-phase, U-phase to W-phase may measure the currents flowing in the six paths, and determine their order. The position detection unit may determine only the order necessary to detect the rotational position of the motor, which need not completely determine all the orders. For example, it may be determined which of the first and second routes is. According to this rotation control device, as described later, the rotation position at the time of stop can be detected within the same angle range as the control at the time of driving the motor, so that the rotation of the motor is more accurately controlled. be able to.

[0008] The rotation control device further includes a table storing the order and the rotation position of the motor in association with each other, and the position detection unit refers to the table and refers to the rotation position of the motor. May be detected. The position detection unit may detect the rotational position of the motor based on a combination of a path having the highest current value and a path having the second highest current value.

[0009] When the control unit detects the rotational position of the motor when the motor is stopped, When driving the motor, a current smaller than the current supplied to the path may be supplied to the path. When detecting the rotational position of the motor when the motor is stopped, the control unit may supply the current to the path for a shorter period of time than supply the current to the path when driving the motor. Good. This prevents the motor from rotating when detecting the rotational position of the motor.

[0010] The apparatus further includes a sample and hold circuit that converts a current flowing in the path into a voltage value and holds the voltage, and supplies a current to the path before measuring the current flowing in the plurality of paths. May hold the voltage value at that time. Thereby, the voltage value of the sample hold circuit can be brought close to the voltage value to be measured in advance, so that the detection accuracy can be improved.

[0011] Another embodiment of the present invention relates to a rotation control method. This rotation control method includes, when a motor including a stator having a plurality of coils and a rotor having a magnetism is stopped, supplying a current to a plurality of different paths including the coils, and controlling a current flowing through the plurality of paths. Measuring the current value, determining the order of the measured current values, and detecting the rotational position of the motor based on the order.

[0012] Still another embodiment of the present invention relates to an electronic device. The electronic apparatus includes: a motor for rotating a disk; a rotation control unit for controlling rotation of the motor; and a read / write control unit for controlling writing or reading of data to / from the disk. Includes a stator having a plurality of coils, and a rotor having magnetism, wherein the rotation control unit supplies a current to a plurality of different paths including the coils when the motor is stopped; and And a position detector for measuring currents flowing through the plurality of paths, determining the order of the measured current values, and detecting the rotational position of the motor based on the order.

The invention's effect

According to the present invention, it is possible to provide a technique for accurately detecting a rotational position at the time of starting a rotor.

Brief Description of Drawings FIG. 1 is a diagram showing a configuration of a rotation control device according to an embodiment.

FIG. 2 is a sequence diagram showing how the motor rotates.

FIG. 3 is a diagram showing a relationship between a rotation angle of a motor at the time of stoppage and a current value when a current flows through a plurality of paths including a coil.

FIG. 4 is a diagram showing an example of a voltage value detected by a detection resistor when a test current is applied.

FIG. 5 is a diagram schematically showing a configuration of a stop position detecting unit.

FIG. 6 is a timing chart for explaining the operation of a stop position detecting unit.

FIG. 7 is a diagram showing another example of the relationship between the rotation angle of the motor at the time of stoppage and the current value when a current flows through a plurality of paths including the coil.

FIG. 8 is a diagram showing a configuration of a magnetic disk drive according to an embodiment.

Explanation of symbols

[0015] 1 magnetic disk drive, 2 disk, 3 magnetic head, 4 read Z write control circuit, 10 rotation control device, 20 control unit, 30 power circuit, 40 position detection unit, 50 stop position detection unit, 52 registers , 54 comparators, 56 selectors, 58 tables, 90 motors, U, V, W coils.

BEST MODE FOR CARRYING OUT THE INVENTION

FIG. 1 shows a configuration of a rotation control device 10 according to the embodiment. FIG. 8 shows a configuration of a magnetic disk drive 1 which is an example of an electronic device equipped with the rotation control device 10 shown in FIG. The magnetic disk drive 1 is mounted on a personal computer or the like, and drives a magnetic disk such as a DVD, CD, HD, FD, or MD. The magnetic disk drive 1 includes a disk 2, a magnetic head 3, a read / write control circuit 4, a motor 90, and a rotation control device 10. The rotation control device 10 controls the driving of a motor 90 for rotating the disk 2 in accordance with a command from a host device such as a personal computer. The read Z write control circuit 4 controls writing and reading of data to and from the disk 2 according to a command from the host device. The read Z write control circuit 4 scans the rotating disk 2 by moving the magnetic head 3 in the radial direction of the disk, and writes data to the disk 2 or reads data from the disk 2. Figure 8 shows a magnetic disk drive as an example of an electronic device. However, the present invention can be applied to various other electronic devices including a motor, such as an optical disk drive.

Returning to FIG. 1, the rotation control device 10 controls the rotation of a sensorless brushless DC motor 90 (hereinafter simply referred to as “motor 90”). The rotation control device 10 includes a control unit 20, a power circuit 30, a position detection unit 40, and a stop position detection unit 50. Since a known technique can be used for the driving method of the motor 90, in the present embodiment, the normal driving method of the motor 90 will be described briefly, and the rotational position of the motor 90 at the time of starting will be described. The explanation focuses on the technology to be detected.

The control unit 20 controls the current supplied to the three-phase coils U, V, and W constituting the stator of the motor 90. The power circuit 30 includes six switching transistors Trl to Tr6, and the current supplied to the coils U, V, and W is turned on and off by turning on and off the transistors Trl to Tr6. The on / off of the transistors Trl to Tr6 is controlled by the control unit 20. When the motor 90 is driven, the position detection unit 40 obtains the potential of the midpoint wiring of the motor 90, detects the induced voltage generated in the coil, and obtains the position information of the motor 90. The control unit 20 obtains control commands such as the rotation direction and the rotation speed of the motor 90, and determines the current to be supplied to the coil of the motor 90 according to the rotation position of the motor 90 detected by the position detection unit 40. Do

The stop position detecting section 50 detects the position of the motor 90 before starting the motor 90. When the test current is supplied to a plurality of different paths including the coil of the motor 90 when the motor 90 is stopped, the stop position detector 50 measures the current flowing in each of the plurality of paths, and measures the measured current value. And the rotational position of the motor is detected based on the determined order. The current flowing through the path including the coil is converted into a voltage by the detection resistor R and measured. The supply of the test current is performed by the control unit 20 and the power circuit 30 in the same manner as when the motor 90 is driven. In order to prevent the motor 90 from rotating due to the test current, it is desirable that the current value of the test current be lower than the current value supplied during driving. desirable.

FIG. 2 is a sequence diagram showing how the motor 90 rotates. The top part of FIG. 2 shows the rotational position of the motor 90, and the middle part of FIG. 2 shows the polarities of the coils U, V, and W excited when current is supplied to the coils 11, V, and W. The lower part of FIG. 2 shows the states of the transistors Trl to Tr6 of the power circuit 30 controlled by the control unit 20. And a sequence number. The drive current is switched at 60-degree intervals based on a certain angle (for example, 0 degree). When the motor 90 is rotated clockwise, the sequence numbers are increased in ascending order. When the motor 90 is rotated counterclockwise, the sequence numbers are increased. The transistors are turned on and off sequentially in descending order. For example, when rotating the motor 90 clockwise from the position of the electrical angular force, the control unit 20 first turns on the transistors Tr3 and Tr4. As a result, the coil U is excited to the S pole and the coil W is excited to the N pole, so that the rotor 92 rotates clockwise. When the rotation angle of the motor 90 reaches 60 degrees, the control unit 20 switches the transistor Tr4 off and the transistor Tr5 on. From this, the coil V is excited to the S pole and the coil W is excited to the N pole, so that the rotor 92 further rotates clockwise.

FIG. 3 shows the relationship between the rotation angle of the motor 90 at the time of stoppage and the current value when current flows through a plurality of paths including the coil. Since each coil is placed in the magnetic field of the rotor 92, which is a permanent magnet, the apparent inductance differs due to the influence of the magnetic field. Therefore, the value of the current flowing through the coil exhibits a rotation angle dependency as shown in FIG. Figure 3 shows the current values of the following six routes.

Thick solid line: U-phase → V-phase (Route 1: Same as sequence No. 4 in Fig. 2)

Thick broken line: V-phase → U-phase (Route 2: Same as sequence No. 1 in Fig. 2)

Solid line: V-phase → W-phase (Route 3: Same as sequence No. 2 in Fig. 2)

Middle broken line: W phase → V phase (Route 4: Same as sequence No. 5 in Fig. 2)

Thin solid line: W phase → U phase (Route 5: same as sequence No. 6 in Fig. 2)

Thin broken line: l ^ g → W phase (path 6: similar to sequence No. 3 in Fig. 2)

Thus, by measuring the current values of the six paths, the positional relationship between the rotor 92 and the coil can be known. In the present embodiment, the current values of the above-mentioned six paths are measured, the measured current values are compared, and the path where the highest current value is measured and the path where the second highest current value is measured The rotation position of the motor 90 is detected from the combination of. For example, when the top two are path 1 and path 4, as shown in FIG. 3, the rotation angle of the motor 90 is between 0 and 60 degrees. By detecting the position of the motor 90 also for the upper two combined forces, the position of the motor 90 can be detected in the same angle range as the current control sequence when driving the motor 90 shown in FIG. . According to the methods described in Patent Documents 1 to 3, for example, a 30-degree force deviates by 30 degrees from the angle range when current control is performed at the time of driving the motor 90, such as a 90-degree force and a 90-150 degree. The position is detected within the range of the angle. For this reason, after detecting the position of the motor 90 at the time of starting, it is necessary to control the power by changing the detected angle by 30 degrees. However, according to the method of the present embodiment, since the position information can be obtained in the same angle range as when the motor is driven, it is possible to drive the motor 90 more accurately by using the obtained position information as it is. For example, the reverse rotation at the time of starting can be suppressed to a minimum.

FIG. 4 shows an example of a voltage value detected by the detection resistor R when a test current flows.

When the supply of the test current is started, current flows through the path including the coil, and the potential difference across the detection resistor R gradually increases. When a current is supplied to each of the six paths, the stop-time position detection unit 50 samples and holds the voltage value after a certain period of time has elapsed from the power transmission and compares the voltage values. In the example of FIG. 4, the top two are path 2 and path 5, so referring to FIG. 2, it can be seen that the position of the motor 90 is between 240 degrees and 300 degrees.

FIG. 5 schematically shows a configuration of the stop position detecting unit 50. When the current is supplied to the path including the coil by the control unit 20 when the motor 90 is stopped, the current flowing through the coil is converted into a voltage value by the detection resistor R and amplified by the amplifier. Switches SW0 to SW2 switch which of the sample and hold SZH1 to SZH3 receives the voltage value converted by the detection resistor R. The switches SW3 to SW6 switch which of the voltage values held in the sample hold S / H1 to S / H3 is input to the comparator 54. The comparator 54 compares the voltage values held in the sample and hold S / H1 to S / H3 and outputs the result to the selector 56. The registers 52a to 52c store data indicating which path the voltage value held in the sample hold SZH1 to 3 is the measurement result. In the present embodiment, since the voltage value is measured through six routes, the registers 52a to 52c only need to be able to store 3-bit data. When the measurement of the six routes is completed, the selector 56 outputs which one of the two upper routes is which. Stop position detector 50 Holds a table 58 in which the combination of the upper two paths and the rotational position of the motor 90 are stored in association with each other, and by referring to the table 58, the rotational position of the motor 90 is detected and the control unit is controlled. Output to 20.

FIG. 6 is a timing chart for explaining the operation of the stop position detecting section 50.

The operation of each configuration of the stop position detection unit 50 may be controlled by the control unit 20 or a control configuration may be provided in the stop position detection unit 50. 20 shall control. The control unit 20 turns on the switch SW0 while supplying the current to the path 1, and inputs the voltage value converted by the detection resistor R to the sample hold SZH1. In addition, the control unit 20 stores “1” in the register 52a in order to record that the measurement result of the path 1 is held in the sample hold SZH1. Subsequently, while supplying the current to the path 2, the control unit 20 turns on the switch SW1, and inputs the measured voltage value to the sample hold SZH2. At this time, "2" is stored in the register 52b. Further, while supplying the current to the path 3, the control unit 20 turns on the switch SW2, and inputs the measured voltage value to the sample hold SZH3. At this time, “3” is stored in the register 52c.

When the measurement results are input to the three sample-and-holds SZH1 to SZH3, the stop-time position detector 50 compares these voltage values and determines the order. First, when the control unit 20 turns on the switches SW3 and SW5 in the period tl, the voltage values held in the sample and hold SZH1 and SZH2 are input to the comparator 54. That is, the measurement result of the route 1 and the measurement result of the route 2 are compared. The comparison result is output to the selector 56. Subsequently, when the control unit 20 turns on the switches SW3 and SW6 during the period t2, the voltage values held in the sample and hold SZH1 and SZH3 are input to the comparator 54, and the measurement result of the path 1 and the measurement of the path 3 The results are compared. The comparison result is output to the selector 56. Finally, during the period t3, when the control unit 20 turns on the switches SW4 and SW6, the voltage values held in the sample hold SZH2 and SZH3 are input to the comparator 54, and the measurement result of the path 2 and the measurement of the path 3 The results are compared. The comparison result is output to the selector 56. As a result, the comparator 54 outputs the three kinds of comparison results to the selector 56 as a 3-bit signal serially. From the three comparison results, the selector 56 selects the path having the lowest voltage value among the three paths. Is determined and transmitted to the control unit 20. Here, it is assumed that the measurement result of the route 1 is the lowest.

The control unit 20 exchanges the measurement result of the route 4 to be performed subsequently with the measurement result of the lowest route transmitted from the selector 56. That is, the control unit 20 that inputs the measurement result of the path 4 to the sample hold (here, SZH1) holding the lowest measurement result transmitted from the selector 56 supplies the current to the path 4 During this operation, the switch SW0 is turned on, and the measured voltage value is input to the sample hold SZH1. At this time, the control unit 20 stores “4” in the register 52a. As a result, the sample hold force SZHl holds the measurement result force of path 4 and the sample hold SZH2 holds the measurement result force of path 2 and the sample hold SZH3 holds the measurement result force of path 3. Subsequently, the voltage values held in the sample / hold S / H1 to S / H3 are compared in the same manner as described above, and the comparison result is output to the selector 56. The selector 56 transmits the lowest route to the control unit 20.

[0028] The same procedure as described above is repeated for the route 5 and the route 6. After the measurement of the route 6 is finally completed, the selector 56 determines the top two routes out of the six routes. The control unit 20 detects the position of the motor 90 from the combination of the upper two paths with reference to the table 58. Thus, even if the motor 90 does not have a sensor for detecting the position, the position of the motor 90 can be accurately detected when the motor 90 is stopped.

FIG. 7 shows another example of the relationship between the rotation angle of the motor 90 at the time of stoppage and the current value when a current flows through a plurality of paths including a coil. In the example of FIG. 7, for example, in the range A around 60 degrees, the current value of the path 2 is higher than the current values of the paths 4 and 6, and the order is different from the example shown in FIG. . In this case, for example, when the determination result indicates that the combination of the path with the highest current value and the path with the second highest current is path 1 and path 2, the stop position detection unit 50 sets the position of the motor 90 to 0. It may be determined that it is in the range of degrees to 60 degrees, or it may be determined that it is in the range of 60 degrees to 120 degrees. That is, range A may be considered to be included in the range of 0 to 60 degrees, or may be considered to be included in the range of 60 to 120 degrees. In the case where the error is increased by performing the above-described determination in which the range in which the order is switched is relatively wide, if the above determination is made, the stop position detection unit 50 may include, for example, only the combination of the first and second places. The angle of the motor 90 may be determined in consideration of the third and lower ranks.

[0030] The present invention has been described based on the embodiments. This embodiment is an exemplification, and it is understood by those skilled in the art that various modifications can be made to the combination of each component and each processing process, and that such modifications are also within the scope of the present invention. It is understood.

[0031] In the embodiment, three sample-and-holds may be used, and a force obtained by comparing currents flowing through six different paths may be used. Further, the configuration for determining the order of the current values is not limited to the configuration shown in FIG. ⁵ , but may be an arbitrary configuration, and the order may be determined by software processing using a general-purpose circuit such as a CPU.

[0032] In the embodiment, the force detected at the position of the motor 90 at 60-degree intervals, for example, taking into account those ranks that are not a combination of the first and second routes, the position may be detected at 30-degree intervals. It is possible.

Before measuring the current value when the current is supplied to the above-described six paths, as a preparation for the measurement, supply the current to any one of the paths and supply the current to the sample hold SZH1, SZH2, and S / H3. The voltage value at that time may be held. For example, a current is supplied twice to the path 1, and the voltage values of the sample hold SZH1, SZH2, and SZH3 are brought close to the values at the time of measurement in advance. As a result, it is possible to improve the detection accuracy of the voltage value in the sample hold SZH1, SZH2, and SZH3.

Industrial applicability

The present invention can be used for a rotation control device that controls the rotation of a motor.

Claims

The scope of the claims

[1] When a motor including a stator having a plurality of coils and a rotor having magnetism is stopped, a control unit that supplies current to a plurality of different paths including the coils,

A position detection unit that measures the current flowing through each of the plurality of paths, determines the order of the measured current values, and detects the rotational position of the motor based on the order;

A rotation control device comprising:

[2] The apparatus further comprises a table storing the order and the rotational position of the motor in association with each other, wherein the position detecting unit detects the rotational position of the motor with reference to the table. The rotation control device according to claim 1.

[3] The position detection unit according to claim 1, wherein the position detection unit detects the rotation position of the motor based on a combination of a path having the highest current value and a path having the second highest current value. 3. The rotation control device according to 2.

[4] The controller is characterized in that, when detecting the rotational position of the motor when the motor is stopped, supplying a smaller current to the path than the current supplied to the path when driving the motor. 4. The rotation control device according to claim 1, wherein:

[5] The control unit, when detecting the rotational position of the motor when the motor is stopped, is shorter than a period for supplying a current to the path when driving the motor, and for a period of time, 5. The rotation control device according to claim 1, wherein a current is supplied.

[6] a sample-and-hold circuit that converts a current flowing through the path into a voltage value and holds the voltage value;

6.A method according to claim 1, wherein a current is supplied to the path before the current flowing through the plurality of paths is measured, and the sample hold circuit holds the voltage value at that time. Rotation control device

[7] supplying a current to a plurality of different paths including the coil when a motor including a stator having a plurality of coils and a rotor having magnetism is stopped;

Measuring the current flowing through each of the plurality of paths,

Determining the order of the measured current values; Detecting a rotational position of the motor based on the order;

A rotation control method comprising:

A motor for rotating the disk,

A rotation control unit that controls the rotation of the motor,

A read / write control unit that controls writing or reading of data to / from the disk,

The motor is

A stator having a plurality of coils;

A rotor having magnetism,

The rotation control unit,

A control unit that supplies current to a plurality of different paths including the coil when the motor stops.

An electronic device, comprising: a position detector that measures currents flowing through the plurality of paths, determines a rank of the measured current values, and detects a rotational position of the motor based on the rank.